In recent years, to avoid collision with a vehicle in front, an automatic brake control device for a vehicle is known which detects a distance between a host vehicle and an obstacle in front from an image captured by a camera or a sensor, such as a laser radar, and makes a brake device operate automatically with a predetermined target deceleration to prevent collision with the obstacle in front when the distance becomes shorter than a predetermined distance.
In the control device for achieving such anti-collision, it is possible to perform the collision avoidance more effectively if control using the engine brake is performed by using the engine brake efficiently.
For example, JP 11-321389A (Reference 1) discloses a device to realize a collision safety function using an automatic brake device in a vehicle in which an automatic transmission is mounted. Specifically, JP 11-321389A (Reference 1) discloses an anti-collision technique for reducing the relative acceleration with respect to an obstacle in front, with which a host vehicle may collide, by shifting an automatic transmission so that the driving force transmitted to the driving wheels is reduced, compared with a case where there is no collision avoidance control, when a distance between the host vehicle and the obstacle in front is smaller than the safety distance when the host vehicle is accelerating.
The technique disclosed in JP 11-321389A (Reference 1) is applied to the automatic transmission in which gear shift determination is performed by a control device. In a vehicle including a manual transmission to switch the gear by the driver, however, even if the anti-collision control function using the automatic transmission described above is realized, collision avoidance cannot be automatically performed with good efficiency since the driver has to select a gear. For this reason, it is not possible to apply the anti-collision technique disclosed in JP 11-321389A (Reference 1).